Injection pump arrangement for multicylinder internal combustion engines



Aug. 30, 1960 E. WALCH ETAL 2,950,681

INJECTION PUMP ARRANGEMENT FOR MULTI-CYLINDER INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 1 Filed Aug. 16, 1957 I g a.

INVENTUPS YdM/mw HTTORNEH 1950 E. WALCH ETA'L 2,950,681

INJECTION PUMP ARRANGEMENT FOR MULTI-CYLINDER INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed Aug. 16, 1957 INVENT'OIPS HTTORNEJ ENJEC'IION PUMP ARRANGEMENT FOR MULTI- CYLINDER INTERNAL COMBUSTION ENGINES Eugen Walsh, Ditzingen, and Ulrich Aldinger, Stuttgart,

Germany, assignors to Robert Bosch G.m.b.H., Stuttgart, Germany Filed Aug. 16, 1957, Ser. No. 678,720

Qlaims priority, application Germany Aug. 22, 1956 7 Claims. (Cl. 103-2) The present invention relates to injection pumps.

More particularly, the present invention relates to that type of injection pump which includes a pair of pistons which reciprocate toward and away from each other so as to provide, respectively, pressure and suction strokes to move fuel from a tank or the like to the several cylinders of an internal combustion engine.

With injection pumps of this latter type considerable difficulty has been encountered in the formation of the passages which lead through the parts some of which are movable with respect to others. For example, it is known to lead such passages through the cylindrical surfaces of elements one of which surrounds the other, but with such a construction it is necessary to construct the parts very precisely and to provide such a small play that, particularly where fuels of low lubricating properties are used, the parts wear away very rapidly and render the injection pump useless after a relatively short time.

One of the objects of the present invention is to provide an injection pump of the above-referred to type which is capable of operating satisfactorily over a long period of time even though the passages of the pump go through surfaces some of which rotate with respect to others.

Another object of the present invention is to provide an injection pump of the above type with a means which will guarantee that the surfaces which cooperate with each other by moving with respect to each other will function properly so as to provide the necessary passages even if the surfaces should become worn.

A further object of the present invention is to provide an injection pump of the above type in which the passages are of relatively simple construction.

It is also an object of the present invention to provied an injection pump accomplishing all of the above objects and composed of simple and ruggedly constructed elements which are very reliable in operation.

With the above objects in view, the present invention includes in an injection pump a cylinder means and a pair of coaxial pistons carried by the cylinder means for movement toward and away from each other, these pistons defining a working chamber between themselves. A drive shaft means is supported for rotation about its axis by a support means, and a cam means cooperates with the pistons for moving the same toward each other along pressure strokes during rotation of the drive shaft means, these pistons moving away from each other along suction strokes respectively after the pressure strokes take place. The support means additionally carries a distributor surface which is fiat and a distributor plate is connected operatively with the drive shaft means to be rotated thereby and has another fiat distributor surface which engages the distributor surface of the support means. An inlet passage means leads through a portion of the support means to the distributor surface thereof and from the latter distributor surface through the distributor surface of the distributor plate and through the latter to the working ited States Patent C) chamber between the pistons so as to deliver to this working chamber fuel during the suction strokes of the pistons, and a discharge passage means leads from the working chamber through the distributor plate to the distributor surface of the latter and from the distributor surface of the support means through the support means to the several cylinders of an internal combustion engine so as to deliver fuel to these cylinders when the pistons carry out pressure strokes. A spring means is provided for urging the distributor surfaces against each other so that the distributor surface of the distributor plate will remain in engagement with the distributor surface of the support means while rotating with respect thereto.

The novel features which are considered as characteristic for the invention are set forth in particlular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Fig. 1 is a partly diagrammatic sectional elevational View of an injection pump according to the present invention;

Fig. 2 is a plan view of a distributor surface of the support means or housing of the injection pump, Fig. 2 showing passages formed in this distributor surface;

Fig. 3 illustrates a rotary distributor surface which cooperates with the distributor surface of Fig. 2 and which is formed with the passages indicated in Fig. 3;

Fig. 4 is a fragmentary, sectional, partly diagrammatic illustration of another embodiment of an injection pump according to the present invention;

Fig. 5 is a diagrammatic illustration of the arrangement of openings of a stationary support means of the embodiment of Fig. 4, these openings leading to one distributor surface;

Fig. 6 is a diagrammatic illustration of the arrange ment of other openings which lead to another distributor surface of the embodiment of Fig. 4, the distributor surfaces provided with the openings of Figs. 5 and 6 being spaced from and parallel to each other; and

Fig. 7 is a diagrammatic illustration of the openings in a rotary distributor plate which provides communication between the openings of Figs. 5 and 6.

Referring to Fig. 1, the fuel is derived from a fuel reservoir 1 by a supply pump 2 which delivers the fuel through a filter 3 to the injection pump. An overflow conduit 4 leads from the filter 3 back to the reservoir 1, and this overflow conduit is provided with an unillustrated non-return valve.

The elements of the injection pump are carried by a support means 6 which forms the housing of the injection pump, and the support means further includes the body 7 which forms the cover of the housing and which is connected in a fluid-tight manner to the housing 6.

The housing or support means 6 rotatably supports a drive shaft means 8, and as is shown in Fig. 1 the drive shaft 8 is rotatably supported by a ball bearing 9 carried by the housing 6. A sealing ring 10 is located between the housing 6 and the drive shaft 8.

The drive shaft means 8 further includes a disc 12 connected with the shaft 8 as by being formed inte grally therewith and rotating with the same, and a cylinder means 13 is fixed to the disc 12 so as to rotate With the disc 12 and the shaft 8, this shaft 8 being driven from the engine.

The cylinder means 13 slidably supports a pair of coaxial pistons 15 for movement toward and away from each other, these pistons 15 defining the working charm ber 53 between themselves.

The pistons 15 move away from each other as a re-' sult of the centrifugal force which acts on the pistons as well as a result of the fuel under pressure in the chamber 53 acting on the pistons to urge the same apart from each other, the fuel pressure being determined by the pump 2. The pistons press outwardly against a pair. of slidernembers 17 which engage the ends of the pistons 15 and which turn with the latter about the axis of the drive shaft 8, these slide members 17 moving radially toward and away from the axis of the drive shaft 8 with the pistons 15, respectively. Each slide member 17 is formed with a channel which forms part of a cylinder and which slidably receives a roller 18.

'A cam means is fixedly carried by the support means 6, 7 and has its inner camming surface in engagement with the rollers 18, the cam means 20 remaining stationary while the cylinder means rotates, and the camming portions of the cam means causes the rollers 18 together with the slide member 17 and the pistons 15 to move toward each other at predetermined times during each rotation of the drive shaft 8. The injection pump illustrated in Fig, l is suitable for use with an eight-cylinder engine, and in this case the inner surface of the annular cam means 20 is provided with-8 sets of diametrically opposed projections extending radially inwardly toward the turning axis of the shaft 8 so that these 8 sets of projections move the pistons 15 toward each other along 8 pressure strokes during each revolution of the drive shaft 8.

A distributor plate 22 has a central axial portion extending downwardly into an upper opening of the cylinder means 13, this downwardly extending portion of the distributor plate 22 being coaxial with the axis of the shaft 8 and being connected to the cylinder means by any suitable means such as pins of the plate 22 extending into axial slots of the cylinder means 13 so that the distributor plate 22 is constrained to rotate together with the cylinder means 13 and the drive shaft means 8, 12 but at the same time is free to shift axially with respect to the cylinder means 13 and drive shaft means. The distributor plate is formed with radial bores which extend to the outer periphery of the distributor plate 22 and which are closed by a ring 23 which is pressed onto the outer periphery of the plate 22.

The top surface of the distributor plate 22 together with the top surface of ring 23, as viewed in Fig. 1, forms a distributor surface 22', and this top surface is fiat and bears against a flat distributor surface 27 carried by the support means and forming part of the bottom face of the cover 7 of the housing 6, 7. A spring means is provided for urging these distributor surfaces toward each other so as to maintain them in engagement with each other, and this spring means is shown in Fig. 1 as taking the form of dished annular springy members 25 arranged between a downwardly directed surface of the distributor plate 22 and an upwardly directed surface of the cylinder means 13 so that the spring means 25 urges the distributor plate upwardly and thus the top. flat distributor surface of the distributor plate 22 is maintained in engagement with the downwardly directed distributor surface 27 of the support means 6, 7.

The cover member 7, which forms part of the support means, as was pointed out above, is formed with a threaded 'bore Which threadedly receives an elongated tubular nipple 29 whose axis coincides with the axis of the drive'shaft 8, and the nipple 29 is formed'with an inner cylindrical urface which slidably surrounds a compensating piston 28 which is slidable along the axis of the nipple 29. The cover member 7 is formed with a bore which extends along the axis of the drive shaft 8 and which feeds into the interior of the nipple 29 so that" fuel under pressure will have access through the bore 30 to the piston 28 inorder to raise the latter'within the nipple 29. A tubular member 32 having a top' closed end is threaded into the nipple 29 and houses in its interior a coil spring 31 which presses downwardly against the piston 28 so as to urge the latter downwardly, and by turning the tubular member 32 the threads there of will cooperate with the threads of the member 29 to cause the member 32 to move in one direction or the other along the axis of the nipple 29 so as to adjust the stress in the spring 31. The bottom free end of the tubular member 32 servesto limit the upward movement of the piston 28, as viewed in Fig. 1. A cap nut 33 threadedly engages the tubular member 32 at an outer threaded surface portion thereof the continuation of which threadedly engages the interior of the nipple 29, and this nut 33 serves to lock the member 32 in an adjusted axial position and in addition the cap nut 3-3 presses against a sealing ring 34 in the manner illustrated in Fig. 1.

The portion 7 of the support means 6, 7 is formed with part of a discharge passage means leading to the several cylinders of the internal combustion engine, and this discharge passage means includes in the illustrated example eight valves, the latter valves being distributed about the piston 28. Each of these valves includes a movable valve member 36 which seats itself in a valve body 37 engaging a sealing ring on a shoulder 39 of the body 7 and pressed against this sealing ring by a tubular member 38 threaded into a threaded bore of the member 7. A valve spring 40 presses downwardly against the movable valve member 36 and upwardly against an inner shoulder of the tubular member 38. These members 3-8 are connected by suitable conduits to the several cylinders of the internal combustion engine. The discharge passage mean formed in the member 7 further includes radial bores 41 closed at their outer ends and respectively leading to the tubular valve bodies 37 in the manner shown in the right half of Fig. 1.

The support means 6, 7 is also formed with an inlet passage forming part of an inlet passage means which leads to the working chamber 53 between the pistons 15, and this inlet passage portion which is formed on the support means is shown as taking the form of a bore 43 extending along the interior of the body 7 down to the distributor surface 27 thereof. The fuel delivered by the pump 2 passes through the inlet passage 43 to the distributor surface '27 and from the latter to the upwardly directed distributor surface of the rotatable distributor plate 22. A throttling member 44 traverses the bore 43 and is provided with an annular groove 45, as shown in the upper left portion of Fig, 1, this groove 45 forming the throttling portion. An unillustrated speed controlling means axially shifts the rod 44 so as to control the'throttling of the fuel flowing along the passage 43.

.As is shown most clearly in Fig. 2, the distributor surface 27 of the cover 7 is formed with a passage means which includes three annular grooves 46 which are concentric with the bore 30. A set of eight radial grooves 47 which are uniformly distributed angularly about the bore 30 interconnect-the pair of inner annular grooves 46, while a similar set of radial grooves 48 interconnects the pair of outer grooves 46, the intermediate groove 46 being common to both pairs, as is evident from Fig. 2.

As may be seen from Fig. 3, the rotating distributor surface of the distributor plate .22 is also formed with three annular grooves, these grooves 49 being indicated in Fig. 3 and being concentric with the axial bore 52 of the distributor plate 22. The grooves. 49 respectively have the same diameter as the grooves 46 and mate therewith 'in the manner indicated in Fig. 1 so as to provide annular spaces formed partly in the cover 7 and partly in the distributor plate 22. The outer groove 49 of Fig. 3 communicates through elongated grooves 50 with the intermediate grooves 49, four such radial grooves 50 being provided. The inlet passage 43 empties into the annular space defined by the cooperating outermost grooves 46 and 49.

The rotatable distributor plate 22 is formed with a transverse bore 51 which is traversed by the axial bore 52 which is of a relatively small cross section at its top end which communicates with the bore 30. The bore 52 communicates with the working chamber 53 so that this chamber 53 communicates also with the bore 51. A pair of axial bores 54 which are diametrically opposed to each other, as shown in Figs. 1 and 3, connect the transverse bore 51 with the outer surface portions of the distributor surface of the plate 22 which surround the top ends of the openings 54 and which are located between the pairs of radial grooves 50, as is evident from Fig. 3. Moreover, these axially extending bores 54 communicate with the annular surface portion of the distributor surface 27 which is located between the two outermost grooves 46 and which is divided up into sections by the radial grooves 48.

The rotary' distributor plate 22 is additionally formed with a bore 55 extending axially from the transverse bore 51 and forming part of the discharge passage means for the injection pump. This bore 55 is located in the space between the pair of innermost annular grooves, and communicates with the annular portion of the surface 27 which is divided up into sections by the radial grooves 47. These portions which are separated by the grooves 47 are formed respectively with bores 56. The several bores 56 which are distributed uniformly about the bore 36 respectively communicate with the plurality of radial bores 41 in the manner indicated in Fig. 1 so that the bores 56 also form part of the discharge passage means. As is evident from Fig. 1 during rotation of the distributor plate 22 the axial bore 55 thereof will successively communicate with the several bores 56.

The ends of the transverse bore 51 of the distributor plate 22 are closed by the ring 23 which is pressed onto the outer periphery of the distributor plate, as was pointed out above.

Where the number of cylinders of the internal combustion engine is different from eight, it is only necessary to change the number of grooves 47 and 43 in the stationary distributor surface 27 correspondingly.

The above-described injection pump operates as follows:

When the pistons move outwardly away from each other so as to provide a suction stroke, the fuel flows past the throttling position 45 along the inlet passage portion 43 to the distributor surfaces and from the latter through the inlet passage portion 51 to the working chamber 53 between the pistons. As soon as the pistons are moved toward each other by the cam means the pressure of the fuel is increased during the pressure stroke of the pistons 15 and the fuel acts through the axial bore 30 to raise the compensating piston 28 and through the discharge passage bore 55 the fuel moves to the discharge valves.

The pressure of the fuel which is increased during the pressure strokes of the pistons 15 causes the fuel to press against the bottom face of the distributor plate 22 within the cylinder means 13 so as to augment the force of the spring and urges the distributor surfaces against each other. The radial grooves 50 of the plate 22 serve to limit the counterforce provided by the fluid pressure act ing on the top distributor surface of the rotary distributor plate 22, this counterforce depending upon the size of the control surface areas which surround the end of the discharge bore :76 and the longitudinal bores 54.

When the pressure drops in the working chamber 53 at the beginning of the suction strokes of the piston 15, the distributor plate 22 is momentarily moved downward 1y away from the distributor surface 27 against the force of the sprin 2-5 by the still high pressure remaining in the fuel at this instant in the discharge passage portions 41 and 56, the pressure of this fuel acting on the flat surface portions of the distributor surface 27 which surround the bottom ends of the bores 56 and which are separated from each other by the radial grooves 47. As a result of this operation the contacting distributing surfaces are always wet with fuel and the wetting thereof with. the fuel is repeated each time the surfaces become separate from each other momentarily. Furthermore, in this Way the friction between the distributor surfaces and thus the wear thereof is diminished. This intermittent movement of the rotary distributor surface away from the stationary distributor surface is of particular advantage when there is no valve in the discharge passage leading to a particular cylinder, because with such a construction there is an effective release of the pressure in the fuel supply conduit after each injection cycle is completed.

During each suction stroke of the pistons 15 the axial bores 54 of the rotary distributor plate 22 are located in the regions of a pair of radial grooves 48, on the one hand, and on the other hand at the same time the discharge bore 55 is located in the region of a radial groove 47. During the pressure stroke the ends of the axial bores 54 are closed by a pair of surface portions of the surface 27 which are located between a pair of radial groves :8. The discharge bore 55 at this time communicates with one of the bores 56. The fuel which is under high pressure has its pressure then reduced when the dis charge bore 55 reaches one of the radial grooves 47 whereupon the fuel is then sucked into the working chamber 53 through the axial bores 54.

In the second embodiment of theinvention which is illustrated in Figs. 47 there is also a support means in the form of a housing 62, and this housing 62 rotatably supports a rotary distributor plate 93 to which the drive shaft means 61 is fixed so that the latter rotates the plate 93. The housing 62 is provided with a cover 63 which is fixed to the remainder of the housing in a fluid-tight manner in any suitable way. An inlet passage portion 64 is formed in the support means or housing 62, and a pressure'release passage 65 as well as a number of discharge passage portions 66 corresponding to the number of cylinders of the internal combustion engine are also formed in the support means 62. A throttling rod 67 extends into the inlet passage portion 64, and the control device for axially shifting the throttling rod 67 is not illustrated. Fig. 4 illustrates the parts 1-4 which correspond to the same parts in Fig. 1 and which serve to deliver fuel to the inlet passage portion 64.

The rotary distributor plate 93 of Fig. 4 forms the bottom wall of a cup-shaped portion 68 connected to the drive shaft 61 for rotation therewith, and this cup-shaped portion 68 fixedly carries a camming means 69 which rotates with the drive shaft 61. Thi camming means 69 is annular and surrounds a pair of coaxial pistons 74 which are supported by a cylinder means 78 for slidable movement toward and away from each other, these pistons 70 defining between themselves the working chamber 79. The two pistons 70 are urged away from each other by the spring 72 which extends into the pistons, and the latter pistons are urged outwardly against a pair of slide members 73 which turnably guide a pair of rollers 74, respectively, these rollers engaging the camming portions of the cam means 69. The rollers 74- are prevented from axial movement by the rings 77 which engage the end faces of the rollers, as shown in Fig. 4.

The cylinder means 78 is formed with an axial bore 80 leading from the working chamber 79 and communicating with a radial bore 82 which is closed at its outer end by a plug 86, this bore 82 forming part of the inlet passage means for leading fuel to the working chamber 79, and the bore 82 has an axial portion extending to the bottom surface of the cylinder means 78 which forms a distributor surface of the embodiment of Fig. 4. In addition, the cylinder body 78 is formed with a plurality of discharge passage portions 83 respectively corresponding to the number of cylinders which are to be supplied with fuel, and these passage portions 83 are placed in the mariner described below successively in communica tion with the several discharge passage PGI'tlOl'lS 66 which are respectively aligned with the discharge passage portions 83; The cylinder means 78 is furthermore formed with an axially extending pressure release bore 84 which extends from the bottom distributor surface of the cylinder means 78 to the radial portion of the bore 82. Pressure valves 85 are respectively located within the several discharge passage portions 83, as is indicated in dotted lines schematically in Fig. 4, the radial portions of these discharge passage portions 83 being closed at their outer ends by suitable plugs which abut at their inner' faces against the outer ends of the springs of the valves 85, as indicated in Fig. 4.

The cover 63 of the'support means 62, 63 of the embodiment of Fig. 4 is provided with downwardly extending projections 87 which respectively extend into recesses formed in the top face of the cylinder means 78 so that these projections .87 which extend into the recesses 88 prevent the cylinder means'78 from rotating with the rotary distributor plate 93. However, the cylinder means- 78 is freely movable downwardly toward the rotary distributor plate 93.' The cylinder means 78 and the cover 63 areformed with coaxial cylindrical bore portions which form extensions of each other and which receive a cylindrical centering member 89 which serves to center the cylinder means 78 with respect to the central axis of the injection pump. The centering cylinder 89 is hollow and receives in its interior a coil spring 90 which abuts at its top end against the cover 63 and at its bottom end against the cylinder means 78 so as to urge the latter downwardly toward the rotary distributor plate 93. The cylinder means 78 is also centered with respect to the central axis of the injection pump, this axis coinciding with the rotary axis of the drive shaft 61, by the cylindrical body 92 which extends partly into a cylindrical recess formed in the top surface portion of the rotary distributor plate 93'and partly into a cylindrical recess formed in the bottom distributor surface portion of the cylinder means 78. This pin 92 in addition to functioning to contribute to the centering of the cylinder means 78 serves to close the bottom end of the axial bore 80 of the cylinder means. The pin 92 is pressed into the cylindrical recess formed in the cylinder means 78. i

It is apparent from the above description that with the embodiment of Fig. 4 the bottom wall of the housing 62 is stationary and the cylinder means 78 also is stationary, and with this embodiment the rotary distributor plate 93 serves to interconnect at the right times the passages of the cylinder means 78 with the passages of the bottom wall of the housing 62. For this purpose the rotary distributor plate 93 is formed with a discharge passage portion 94 which successively places the aligned pairs of discharge passage portions '83 and 66 in communication with each other during rotation of the plate 93 with the drive shaft 61, the latter being driven from the engine. Furthermore, the rotary distributor plate 93 is formed with six inlet passage portions 95 extending axially through the plate 93 and being uniformly distributed about the axis thereof and with six pressure reducing passage portions 95, the embodiment of Fig. 4.

being used for a six-cylinder engine so that the cam means 69'has six pairs of diametrically opposed camrning portions uniformly distributed about the axis of the drive shaft 61 to engage the rollers 74 for moving the pistons 70 toward each other along six pressure strokes during each rotation of the drive shaft 61. The pressure reducing bores 96 formed in the rotary distributor plate 93 do not extend parallel to the turning axis thereof but are inclined in the manner indicated in Fig; 7 so that they will provide communication between the pressure reducing bore portion 84 and the pressure reducing bore portion 65, the latter being located adjacent to the inlet bore portion 64'and'oommunicating with the fuel supply reservoir 1.

Fig. 5"illustrate's the arrangement of the ends of the discharge bore portions 66, the inlet bore portions 64, and the pressure reducing bore portion 65 in the top surface 62' of the bottom wall of the housing 62, this top surface 62' forming'one of the distributor surfaces of the embodiment of Fig. 4. Fig. 6 illustrates the arrangement of the ends of the discharge bore portions 83, the inlet bore portion 82, and the pressure reducing bore portion 84 in the bottom surface 78 of the cylinder means 78 which bottom surface 78' forms another of the distributor surfaces of the embodiment of Fig. 4. These distributor surfaces are in slidable engagement with the top surface 93' and bottom surface 93 of the rotary distributor plate 93, the top surface 93 andbottom surface 93" forming, respectively, two more distributor surfaces of passes through the inlet passage portion 64 and the bore portions of the rotary plate 93 into the inlet passage portion 82. of the cylinder means 78 and from the latter along the am'al passage 8% into the working chamber 79, the several axial bores 95 of the rotary distributor plate 93 communicating successively with the bore portions 64 and 82 so that the intermittent delivery of the fuel during the successive suction strokes of the piston 70 is provided in this Way. The cam means 69 causes the pistons 7 i to move toward each other along their pressure strokes after each suction cycle and during this time the shaft 61 has turned through an angle sufficient to place the discharge passage portion 94 of the rotary plate 93 in communication with a pair of aligned discharge bore portions 83 and 66, so that fuel is delivered to one of the cylinders in this way. Shortly before the discharge bore portion 94 is closed by turning beyond the bore portions 83 and 66 the rotary plate 93 has turned to a position which places one of the pressure reducing bore portions 96 of the rotary plate in communication with the other pressure reducing bore portions 84 and 6 5, so that in this way the pressure in the discharge passage means 83, 94, 66 drops. The pressure reducing passage means can be arranged with respect to the discharge passage means in such a way that either the entire strokes of the pistons, that is, the entire pressure strokes thereof, can be used for delivering fuel to the cylinders of the internal combustion engine, or only a portion of the pressure strokes of the pistons 78 may be used for this purpose, the pressure reducing passage means coming into play for the remainder of the portion of the pressure strokes of the pistons 7 (i.

The above-described cycle of operation of the embodiment of Fig. 4 is repeated six times for each revolution of the drive shaft 61, in the case of the injection pump of Fig. 4 which is used with a six-cylinder engine in the illustrated example. 7

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of injection pumps diflfering from the types described above.

While the invention has been illustrated and described as embodied in injection pump for multi-cylinder engines, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the 9 standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an injection pump, in combination, cylinder means; a pair of coaxial pistons slidably supported for axial movement toward and away from each other by said cylinder means and defining between themselves a single working chamber; drive shaft means; support means supporting said drive shaft means for rotation; cam means cooperating with said pistons for moving the same toward each other along pressure strokes at predetermined times during rotation of said drive shaft means, said pistons moving away from each other during suction strokes at other predetermined times during rotation of said drive shaft means; a fiat distributor surface carried by said support means; a distributor plate connected to said drive shaft means for rotation therewith and having a fiat distributor surface engaging and rotating with respect to said distributor surface carried by said support means; inlet passage means leading to said single Working chamber between said pistons for delivering fuel to said working chamber during the suction strokes of said pistons, said inlet passage means being formed in part in said support means and leading to said distributor surface carried thereby and said inlet passage means being formed in part in said distributor plate and leading from the distributor surface of the latter through said plate toward said working chamber; discharge passage means leading from said single working chamber to the several cylinders of an internal combustion engine for delivering fuel to said cylinders, respectively, during pressure strokes of said pistons, said discharge passage means also being formed in part in said distributor plate and leading to said distributor surface thereof and in part in said support means and leading from the distributor surface of said support means; and spring means urging said distributor surfaces toward each other.

2. In an injection pump, in combination, support means; drive shaft means rotatably carried by said support means; cylinder means carried by said drive shaft means for rotation therewith; a pair of coaxial pistons slidably supported by said cylinder means for axial movement toward and away from each other and defining between themselves a single working chamber; cam means carried by said support means and cooperating with said pistons during rotation thereof together with said cylinder means and drive shaft means for moving said pistons toward each other along pressure strokes at predetermined times during rotation of said drive shaft means and cylinder means, said pistons moving away from each other along suction strokes at other predetermined times during rotation of said drive shaft means; a distributor plate carried by said cylinder means for rotation therewith and for axial movement with respect thereto along the axis of said drive shaft means, said distributor plate having a flat distributor surface; a flat distributor surface carried by said support means and engaging said flat distributor surface of said plate; spring means located between said plate and cylinder means and urging said plate toward said distributor surface of said support means so as to urge said distributor surfaces toward each other; inlet passage means leading to said single working chamber between said pistons, said inlet passage means being formed in part in said support means and leading to said distributor surface thereof and in part in said distributor plate and leading from the distributor surface of the latter to said working chamber so that said inlet passage means will deliver fuel to said working chamber during suction strokes of said pistons; and discharge passage means leading from said working chamber to the several cylinders of an internal combustion engine for delivering fuel to said cylinders, respectively, during pressure strokes of said pistons, said discharge passage means being formed in part in said plate and leading to said distributor surface thereof and in part in said support means and leading from said distributor surface of the latter.

3. In an injection pump, in combination, support means; drive shaft means rotatably carried by said support means; cylinder means carried by said drive shaft means for rotation therewith; a pair of coaxial pistons slidably supported by said cylinder means for axial movement toward and away from each other and defining between themselves a single working chamber; cam means carried by said support means and cooperating with said pistons during rotation thereof together with said cylinder means and drive shaft means for moving said pistons toward each other along pressure strokes at predetermined times during rotation of said drive shaft means and cylinder means, said pistons moving away from each other along suction strokes at other predetermined times during rotation of said drive shaft means; a distributor plate carried by said cylinder means for rotation therewith and for axial movement with respect thereto along the axis of said drive shaft means, said distributor plate having a flat distributor surface; a fiat distributor surface carried by said support means and engaging said flat distributor surface of said plate; spring means located between said plate and cylinder means and urging said plate toward said distributor surface of said support means so as to urge said distributor surfaces toward each other; inlet passage means leading to said single working chamber between said pistons, said inlet passage means being formed in part in said support means and leading to said distributor surface thereof and in part in said distributor plate and leading from the distributor surface of the latter to said working chamber so that said inlet passage means will deliver fuel to said working chamber during suction strokes of said pistons; and discharge passage means leading from said working chamber to the several cylinders of an internal combustion engine for delivering fuel to said cylinders, respectively, during pressure strokes of said pistons, said discharge pass-age means being formed in part in said plate and leading to said distributor surface thereof and in part in said support means and leading from said distributor surface of the latter, said spring means having a force which is overcome by the force of the fuel pressure at the termination of each pressure stroke so that the fuel moves said plate against the force of said spring means in a direction which separates said distributor surfaces from each other momentarily after each pressure stroke of said pistons.

4. In an injection pump, in combination, support means having a flat distributor surface; a distributor plate rotatable with respect to said support means and having a fiat distributor surface engaging said flat distributor surface of said support means; drive shaft means connected to said distributor plate for rotating the same; cylinder means connected with said support means so as to be substantially immovable with respect thereto; a pair of pistons coaxially carried by said cylinder means for reciprocating movement toward and away from each other and defining a single working chamber between themselves; cam means connected to said distributor plate for rotation therewith and cooperating with said pistons for urging the same toward each other along pressure strokes, said pistons moving away from each other along suction strokes respectively after said pressure strokes; spring means urging said distributor surfaces toward each other; inlet passage means leading to said working chamber for delivering fuel thereto during suction strokes of said pistons, said inlet passage means being formed in part in said support means and leading to said distributor surface thereof and in part in said distributor plate and leading from said distritmtor surface of the latter toward said working chamber; and discharge passage means leading from said single working chamber to the several cylinders of an internal combustion engine which are respectively supplied with fuel during the pressure strokes of said pistons, said discharge passage means being formed in part in said distributor plate and leading to said distributor surface thereof and in part in'said support means and leading from the distributor surface of the latter.

5. In an injection pump, in combination, support means having a distributor surface; a distributor plate rota table with respect to said support means and having a pair of opposite distributor surfaces one of which engages and is rotatable with respect to said distributor surface of said support means; drive shaft means connected to said distributor plate for rotating the same with respect to said support means; cylinder means having a distributor surface engaging the other of said distributorsurfaces of said distributor plate; a pair of coaxial pistons carried by said cylinder means for reciprocation toward and away from each other and said pistons defining a single working chamber between themselves; cam means connected to said distributor plate for rotation therewith and acting on said pistons to move the same toward each other along pressure strokes, said pistons moving away from each other along suction strokes which take place after said pressure strokes; means-connecting said cylinder means to said support means for preventing rotation of said cylinder means with 'said distributor plate while freeing said cylinder means for axial movement toward said distributor plate; spring means cooperating with said support means and cylinder means for urging the latter toward said distributor plate, so that said spring means urges said distributor surface of said cylinder means and said other distributor surface of said distributor plate toward each other as well as said distributor surface of said support means and said one distributor surface of said plate toward each other; inlet passage means leading through said support means, said distributor plate and surfaces, and said cylinder means to said working chamber between said pistons for delivering fuel thereto during suction strokes of said pistons; and discharge passage means leading from said single working chamber through said cylinder means;

said distributor plate and distributor surfaces, and said support means to the several cylinders of an internal combustion engine for respectively delivering fuel thereto during pressure strokes of said pistons.

6. In an injection pump, in combination, support means having a distributor surface; a distributor plate rotatable -with respect to said support means and having a pair of opposite distributor surfaces one of which engages and is rotatable with respect to said distributor surface of said support means; drive shaft means connected to said distributor plate for rotating the same with respect to said support means; cylinder means having a distributor surface engaging the other of said distributor surfaces of said distributor plate; a pair of coaxial pistons carried by said cylinder means for reciprocation toward and away from each other and said pistons defining a single working chamber between themselves; cam means connected to said distributor plate for rotation therewith and acting on said pistons to movethe same toward each other along pressure strokes, said pistons moving away from each other along suction strokes which take place after said pressure strokes; means connecting said cylinder means to said support means for preventing rotation of said cylinder means with said distributor plate while freeing said cylinder means for axial movement toward said distributor plate; spring means cooperating with said support means and cylinder means for urging 12 the latter toward said distributor plate, so' that said spring means urges said distributor surface of said cylinder means and said other distributor surface of said distributor plate toward each other as well as said distributor surface of said support means and said one distributor surface of said plate toward each other; inlet passage means leading through said support means, said distributor plate and surfaces, and said cylinder'rneans to said working chamber between said pistons for delivering fuel thereto during suction strokes of said pistons; discharge passage means leading from said single working chamher through said cylinder means, said distributor plate and distributor surfaces, and said support means to the several cylinders of an internal combustion engine for respectively delivering fuel thereto during pressure strokes of said pistons; and a pair'of coaxial cylindrical bodies arranged along the axis of said drive shaft and cooperating with said cylinder means and respectively with said distributor plate and support means for centering said cylinder means with respect to the axis of said drive shaft and distributor plate.

7. In an injection pump, in combination, cylinder means; a pair of coaxial pistons slidably' supported for axial movement toward and away from each other by said cylinder means and defining between themselves a single working chamber; drive shaft means; support means supporting said drive shaft means for rotation; cam means cooperating with said pistons for moving the same toward each other along pressure strokes at predetermined times during rotation of said drive shaft means, said pistons moving away from each other during suction strokes at other predetermined times during rotation of said drive shaft means; a flat distributor surface carried by said support means; a distributor plate connected to said drive shaft means for rotation therewith and having a flat distributor surface engaging and rotating with respect to said distributor surface carried by said support means; inlet passage means leading to said single working chamber between said pistons for delivering fuel to said working chamber during the suction strokes of said pistons, said inlet passage means being formed in part in said support means and leading to said distributor surface carried thereby and said inlet passage means being formed in part in said distributor plate and leading from the distributor surface of the latter through said plate toward said working chamber; discharge passage means leading from said working chamber to the several cylinders of.

an internal combustion engine for delivering fuel to said cylinders, respectively, during pressure strokes of said pistons, said discharge passage means also being formed in part in said distributor plate and leading to said distributor surface thereof and in partrin said support means and leading from the distributor surface of said support means; and spring means urging said distributor surfaces toward each other, the portions of said inlet passage means which are located at said distributor surfaces being spaced from the axis of c said drive shaft means by radial distances which are diflierent from the radial distances from said axis to the portions of said discharge passage means which are. located at said distributor surfaces.

References Cited in the file of this patent UNITED STATES PATENTS Overbeke May 8, 1951 2,552,449 2,557,508 Leibing June 19, 1951 2,588,644 2,634,688 Iakobsen Apr. 14, 1953 2,641,238 Roosa June 9, 1953 2,716,945 Presnell Sept. 6, 1955 

